A question for all the air conditioning experts


Suppose I have a space that requires 2 tons to cool (about 20,000 BTU), but I notice high tonnage AC units cost more to buy and to install. So I’m wondering is there any advantage to having one large AC unit or 2 smaller AC unit that equals the same tonnage?

I found a place that will install a .8 ton AC unit (used) for 6500 including installation, ductless unit obviously. They’re old but I don’t see the reason to spend 20,000 NT or more on a .8 ton inverter AC unit anyways when it seems (to me anyways) inverter only really works if you’re installing a 3 ton unit in a tiny little space (as they can reduce their cooling capacity at will therefore save electricity). I just figure I can install 2 such units in the larger main workspace and I can turn them both on if one isn’t cutting it.

I’m not even sure why it makes any sense to throw old units away that uses R22 when the unit is perfectly good and the newer refrigerants not only cost more, but require more expensive/thicker plumbing to work. I mean I don’t expect to say save more than 200nt a month using say the expensive inverter AC vs. an old one that works just as well (assuming they are properly sized for the space to be cooled).

Is R22 really that bad and inefficient?



If you only have a small space, it probably doesn’t make any difference what you do (especially bearing in mind the dirt-cheap cost of electricity in Taiwan).

In general terms, all heat pumps have a maximum efficiency point which is typically at 70-80% of maximum rated power output. So the ideal scenario is to have your aircon slightly over-rated for your space. That may not actually help if the device has an on-off thermostat design and runs at or close to its maximum power output when the thermostat is on … as cheaper ones will.

Newer aircon units tend to be more efficient than older ones, but that’s not really related to the refrigerant type - it’s just smarter optimisation of the cooling cycle.



I may end up paying 6nt per kwh because of how electricity is shared here. Basically what they like to do is have several rental units share the same meter. Taipower charges based on usage, first 1000kwh or so per month the electricity is around 4nt per kwh at worst, but once you go above 1500kwh per month they ramp up the price dramatically to discourage people from being wasteful. They have a smart meter pricing scheme where they charge you based on time of the day (during the day it’s like 5nt per kwh and at night it’s around 1.5)

How much are electricity in the old country?



OK, that could quickly add up if you run your aircon all evening and at night and they’re not passing on the off-peak rates to you. 12hrs of usage could easily be 60NT+.

Go for a mid-priced inverter type, and oversize it slightly. Bear in mind that your optimal cooling capacity will depend greatly on where you set your thermostat (ie., how cool you like it). If you’re happy with 25-26’C, you can get away with a very small unit.

Electricity back in blighty is about 15p/kWh, I think. NT$6.



Why inverter types? They’re more than twice as expensive as non inverter types and so it would take a LONG time for it to pay for itself. As in if I am using only 10% less electricity for a given cooling capacity…

Edited to say I looked up PG&E and boy they are expensive!

Average of 35 cents per kwh which is about 10nt per…

I used to hear San Franciscans complain how they can’t afford heating and cooling because of the high rates… and they pay a lot for water too!



I think you’ll find it’s more like 30-40% saving compared to one of those ancient window-type units.

Do you have an aircon at the moment? If so, just buy a cheap power meter and measure how much electricity you actually use. If you have a submeter already installed, just take a reading before you go to sleep and another when you wake up. If you use the aircon a lot, a brand-new inverter model will probably pay for itself in 2-3 years, but I agree it would be pointless if (a) your power consumption is modest and (b) you don’t intend to stay in that place long-term.



Right now the place has no aircon. I will install one, there is a guy on ruten that offers a split unit for 3500nt (another 3000 to install it). I suppose splits are more efficient but by how much? Windows unit seems ok but they do have problems with sealing, and they require a window without bars which is not always possible. I was thinking of in the future install 2 such units on the outside (larger) space.

I just don’t want to pay 24,000 for a brand new inverter unit that’s only good for a 4 ping room (which is what all the major retailers are selling for)



if you sleep in the room, consider that a split system is WAAAY quieter, as well as keeping the hot parts of the machine outside. window units are also a pain to properly insulate around the machine, and tend to leak a lot of heat back into the room through the ‘unused’ parts of the window.



Presumably this is a second hand unit? I know money may be tight but for not a huge amount more you could get a brand new unit and not have to worry about breakdowns or repair costs for at least a year.



I agree that the issues of noise and reliability are important considerations. You definitely get what you pay for where aircon units are concerned, and the cheap ones are usually a bit crap on several different measures.



I think your biggest problem is splittinhg the electricity bill. Are you sure there is no way you can get your own meter? I knwo of people who get 10 thousand NTD or more per month as bill from their landlord… and they are never home, turn on teh AC only a couple of hours, etc.

OTOH, do not underestimate the power of low consumption units. Seriously, I pay very little, but since I changed to a more modern fridge, I pay even less, half of what I used to. Air conditioners are more and more power eficient each year. They have a littel scale that lets you know how good they are at it. I buy appliances at 1, never above that.



Taipower is quite complicated about who they will let you have an electrical account.

If you live in one floor, and you have say 4 residents living in their separate room, Taipower WILL NOT let each residents get their own meter. Only one meter per floor.

I suspect because if they allowed every room to have its own meter then people could do that to get around the rationing requirement by having 10 accounts tied to every single room or appliance in the house. I think the costs we pay (around 2-4nt per kwh) is actually heavily subsidized and so Taipower actually spends far more generating the power. And since we’re still afraid of nuclear energy we have to use expensive or polluting generation methods… I do notice that most other countries (developed countries that is) actually charge more than 6nt per kwh as their minimum rate, and their higher rates are far higher (as much as 15nt per kwh!). 6nt per kwh is actually the highest Taipower will ever charge for electricity under any circumstance. I believe they subsidize electricity rates to boost manufacturing economy.

All the AC units at one costs a MINIMUM of 30,000nt, even for a small split unit. They may be very efficient but are expensive and the subsidies that the government give on those units are peanuts. Unless someone wants to lend me money to buy those expensive units. And to be honest with you, exactly how much is those 1’s are saving on electricity when you can’t really go over 80% efficient as far as heat removal goes? I mean a 2.8kw cooling AC unit will always draw around 800 watts per hour. That’s pretty efficient if you think about it…

At 6nt per kwh 10,000 should buy you around 1600kwh. There is something SERIOUSLY wrong if you are using that much electricity per month in an apartment. I used to live in an entire floor and I use AC and I don’t even use more than 500kwh every 2 months. And that’s using used/inefficient split and window units.



TAIPOWER is …weird. I have seen reports on the news of scare tactics where mobster steal people´s meter rights, they apply for an electricity meter under the address wher ethey want to “persuade” people to sell/move. Seems weird that such can be done in this day and age but ther eis “a loophole”.

I live in an area designated for veterans and government employees, so we pay less for our electricity than average. We used to live on the main road and pay over 10k… we were on a business/industrial building and we had a drain of electricity sowmehere - with everything unplugged, the meter kept running… fast. Also, when we lived in Shida, it was over 10k, mostly because of the area plus a roomamate that insisted on setting the AC at 17 degrees…



Like I said, if you’re paying 10k per month on a flat something’s seriously wrong and if someone’s stealing electricity (meter kept running even though main breaker is off) you need to talk to your landlord pronto. Show them the meter running with everything turned off and check the circuits and see where the cables are going.

1600 kwh is a lot of power for a small flat to be using and that will raise eyebrows. Maybe someone stole your power so they can grow pot or something.

If my meter was turning fast with everything turned off, I’d be telling the landlord that I REFUSE to pay the bill until he can figure out exactly who’s stealing my electricity.

Hell, the only place that I see using that much power is a FamilyMart I used to work for… they have probably a 4 ton AC unit, a walk in fridge, a few freezers, a few open fridges, all running basically 24/7.



Where are you getting this pricing from? Even B&Q who I would not consider cheap sell units rated for around 5 ping at almost half that delivered, and installed for window types.




What I’m referring to is the ones where they have this chart showing how energy efficient a particular unit is. 1 being most efficient, and 5 being least. Only those with a rating of 1 or 2 are eligible for subsidies and it’s a very small subsidy. Those AC units with a rating of 1 cost a LOT of money. This is the cheapest one with a rating of 1 that I have found, and it’s for a very small room.




It’s 20K ish at a chain store. If you’re thinking of buying a second hand unit for ~7K fitted then forget about efficiency ratings, get something good value with a solid warranty.

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Well, that is how we ended in a new apartment!

What I mean to say is shared meters is asking for trouble, to be avoided if possible. However, since you have no control over this issue, at least controlling what you can may save you money.

One has to be reasonable with the costs and expect reasonable costs. A good air conditioning unit is a good, lasting, reasonable investment.

Mine are expensive but I pay them in installments. Try 全國.

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I’ve heard they have some sort of price-matching thing at 全國 - they guarantee to be cheaper than anybody else.



those price match thing has a huge catch though…

It has to be from one of the major retailers or chain. You know, Sunfar, Tsankuen, Carrefour, B&Q, etc. and not a mom and pop store (who will always be cheaper than the major retailers).

They already agreed on how much the prices are going to be so there are going to be little, if any price matching going on. They aren’t stupid either.

Also I looked at the major retailers and none of them has regular AC units on display, all they have are the inverter stuff. Which is why my landlord says don’t ever go with a major retailer, the mom and pop HVAC stores are going to have the best prices.